Gas turbine engines used in aircraft often include a fan assembly that is driven by an engine core to push air through the engine and provide thrust for the aircraft. A typical fan assembly includes a fan rotor having blades and a fan case that extends around the blades of the fan rotor. During operation, the fan blades of the fan rotor are rotated to push air through the engine. The fan case both guides the air pushed by the fan blades and provides a protective band that blocks fan blades from being thrown out of the fan assembly in case of a blade-off event in which a fan blade is released from the fan rotor.
Fan cases sometimes include metallic shrouds, composite reinforcements, and sound attenuation devices (sometimes called dampers). The inclusion of metallic shrouds can cause fan cases to be heavy due to the size and strength required of a fan case. Composite reinforcements are generally used to strengthen metallic shrouds and may be coupled to metallic shrouds by hanger features that extend from the metallic shrouds or by adhesives that provide a permanent bond to the metallic shrouds. The sound attenuation devices are sometimes mounted to the metallic shrouds and are adapted to reduce the noise produced by rotation of the fan rotor in the fan case.